Changes in phase and microstructure were investigated in the SiC-AlN ceramics prepared by pressureless sintering using yttrium aluminum garnet (YAG) as a sintering aid at 200$0^{circ}C$ and 210$0^{circ}C$. The SiC/AlN ratio made a remarkable difference in densification, phase relations and the morphology of grains. In the AlN-rich composition, major phase was 2H and microstructure was composed of the densified equiaxed grains irrespective of the sintering temperatures. While those sintered at 200$0^{circ}C$ were porous with major phase being 3C, the rod-like and the equiaxed grains were coexisted when sintered at 210$0^{circ}C$ in the SiC-rich composition.